The invention generally relates to blocking a leakage current.
A typical semiconductor package includes one or more semiconductor dies that contain integrated circuitry and external terminals (leads or bumps, for example) to electrically connect the package to other electrical components. The die(s) typically contain bonding pads, which are exposed sites on the die(s) at which electrically conductive bonds are formed between the integrated circuitry and the external terminals of the semiconductor package.
Each external terminal of the semiconductor package may potentially communicate an electrostatic discharge (ESD) to the integrated circuitry of the package. An ESD is a rapid and spontaneous transfer of electrostatic charge between two bodies, which is initiated by an electrostatic potential difference between the bodies. Thus, an ESD may occur, for example, when a particular external terminal of the semiconductor package contacts a body (a machine, a human body, a shipping material, etc.) that has a different electrostatic potential. The ESD typically produces a voltage fluctuation, or spike, on the external terminal; and this voltage spike may be capable of damaging integrated circuitry of the semiconductor package.
For purposes of preventing damage from an ESD, a conventional integrated circuit may have an ESD protection circuit for each bonding pad to reduce, or dampen, an ESD-induced voltage spike that may otherwise propagate to the pad and onto other circuitry that is electrically coupled to the pad.